Almost from the advent of the first motor vehicle powered by an internal combustion engine, engine speed control has been effected by an accelerator pedal mechanically coupled through the vehicle fire wall to an engine "speed regulator" such as a carburetor. When no pressure was applied to the pedal, the engine ran at some preset idle speed. And when vehicle-accelerating pressure was applied to the pedal, the pedal/carburetor linkage opened passages in the carburetor to admit more fuel to the engine. The linkage was "custom-configured" for the particular vehicle, engine and carburetor.
Much more recently, engine and vehicle manufacturers have turned to electrical and electronic engine speed control systems which sense engine temperature, engine load and the like and automatically control pump-fed fuel injectors to cause the proper amount of fuel to be admitted to the engine. Such systems are vastly more flexible in the way they can be installed in the vehicle and applied to the engine.
As but one example of improved flexibility in application, it is no longer required to extend a mechanical linkage through the vehicle firewall and provide appropriate sealing devices to prevent air leakage into the passenger compartment. Rather, electrical wires can be extended from the accelerator pedal mechanism to the electronic speed control on the engine.
A typical electrical engine throttle control system uses an electrical sensor, the output signal of which is a function of the position of the accelerator pedal. That is, the sensor "senses" pedal position between idle speed and maximum engine speed and the resulting signal is used by the electronic engine speed control system for engine speed regulation. A common sensor is embodied as a potentiometer or "pot" having a rotating stem. As the accelerator pedal is depressed and released, the stem rotates and an appropriate output signal results.
Examples of arrangements having an accelerator pedal and a sensor coupled thereto are disclosed in U.S. Pat. Nos. 4,958,607 (Lundberg); 4,976,166 (Davis et al.); 5,133,225 (Lundberg et al.); 5,237,891 (Neubauer et al.); 5,241,936 (Byler et al.) and 5,321,980 (Hering et al.). U.S. Pat. No. 5,133,321 (Hering et al.) discloses a resistive-type throttle control and idle-validation sensor combined into a single component.
While earlier arrangements have been generally satisfactory for the intended use, they are not without disadvantages. A notable disadvantage is that the pedal assembly hardware must be configured to accommodate a particular sensor made by a particular manufacturer. For example, the combined control and validation sensor disclosed in the above-noted Hering et al. patent is to be used with Cummins CELECT.TM. electronic fuel control system. The patent goes on to explain that the sensor may be "adapted" to operate with a variety of control systems and control devices.
Yet another apparent disadvantage is based upon the understanding that the arrangement of the Byler et al. patent uses a single sensor which may be adapted to any one of several different engines and engine control systems. But engine and vehicle builders may wish to use their own sensor or one specified by them rather than one supplied by the manufacturer of the pedal hardware.
It is most preferable that an electronic accelerator pedal assembly be mounted on the front wall, often referred to as the fire wall, of the passenger compartment. The arrangements shown in the above-noted Byler et al. and Lundberg patents mount in that fashion. But those shown in the above-noted Davis et al. and Lundberg et al. patents mount adjacent to the floor where they are more susceptible to damage by water, dirt, foot-borne road salt and the like.
Yet another disadvantage of some prior art arrangements is that the accelerator pedal is biased to the engine idle position by a single spring. The apparatus shown in the above-noted Hering et al. patent is a example. But if the single spring fails, the pedal may move to a position representing some engine speed above idle, not a desirable condition.
The arrangement shown in the above-noted Byler et al. patent has pedal-biasing springs which are coiled flat ribbons and which are confined in a drum-like enclosure. If they become wet, such springs dry less easily than exposed springs and are not easily replaced. And, seemingly, manufacturing tooling for such arrangement may be more costly than is necessary in view of the invention.
An improved vehicular accelerator pedal apparatus which addresses disadvantages of prior art arrangements would be an important technical advance.